Time to buy solar panels

[Kevin Kaldenbach]

I am ready to purchase solar panels and had a few questions. There are so many opinions about solar, series or parallel, what kind of controller regular or MPPT, go cheep on the panels or get a brand name. You get the point.

My CD31 has had all the lights converted to LED, the fridge has a keel cooler and draw only 3-5 amps, and my radar is broadband so I think I have done my homework on designing the house electrical systems. Oh and my house bank is 460 amps.

I figure about 200 to 250 watts would go long ways.

Can I mount these panels on a 7/8 bimini frame or do I need one inch? Does anyone know who sells a bimini kit with a 1 inch frame?

I am thinking of putting my panels in parallel to lesson the chance of problems with shading. Will I still need the expensive MPPT controller?

[sharkbait]

I strongly recommend the MPPT controller.

[Maine Sail]

I am ready to purchase solar panels and had a few questions. There are so many opinions about solar, series or parallel, what kind of controller regular or MPPT, go cheep on the panels or get a brand name. You get the point.

Do not go cheap on the regulator. The "shunting" controllers can be very slow to top up the batteries do to the span between on & off voltages. They basically turn the controller on & off once the batts hit absorption. Some even have an ON voltage as low as 12.9 volts which is ridiculous. Once you hit absorption the on time may be a few seconds to a minute but then the off time, waiting for the surface charge to dissipate, can take a minute and a half or more so that last 10% of charge can take a very, very long time. With AGM batteries it occurs even slower.

I have been using and installing the Genasun MPPT controllers and they are top quality, simple, fast and well built. They are specifically designed for use with small panels up to 150W. With most big brand MPPT's you'll see little benefit below 150W but the Genasun controllers are specifically tuned for small arrays and to use any excess voltage as efficiently as possible.

The Genasun controllers are also very reasonably priced. I have two sitting in my shop for installs next week and have all but stopped installing Morningstar or Blue Sky on smaller panel jobs.

My CD31 has had all the lights converted to LED, the fridge has a keel cooler and draw only 3-5 amps, and my radar is broadband so I think I have done my homework on designing the house electrical systems. Oh and my house bank is 460 amps.

This is one of the best things you can do, conservation.

I figure about 200 to 250 watts would go long ways.

That's a big array and would likely support most of your loads if installed well...

Can I mount these panels on a 7/8 bimini frame or do I need one inch? Does anyone know who sells a bimini kit with a 1 inch frame?

I would not put that much panel up there and even with 1" be sure to get the heavy walled stuff. A single 130W maybe but 250W is a lot..

I am thinking of putting my panels in parallel to lesson the chance of problems with shading. Will I still need the expensive MPPT controller?

Very good choice. You'll give up some MPPT conversion but in the world of sailboats I find the losses are worse from shading.

For bigger panels I like the Kyocera's but try to find a "traditional" junction box version. I really dislike the grid tie boxes...

[Larry DeMers]

I have a single Kyocera 80W panel, mounted on the starboard, amidships, on a swing-out frame system I made). Along with a wind generator and 440Ah of Trojan T105's (going on 7 years old and still great!), we make enough juice to stay at anchor for 3-4 days without running the engine at all. This supports a load of 40-60 Ah daily.

This load consists of running the reefer system (freezer and refrig section, keeping 22 deg/42deg on avg. in the box), lighting (all LED), flat panel tv and DVD stereo system, anchor light (LED) and inverter. Pretty typical, I expect, for liveaboards.

As I said, that was with a single 80W panel. I will be adding another panel to the port amidship location next year, probably another Kyocera 85W panel. That will finish off our energy upgrade started a few years ago, and will be more than sufficient for us.

I am trying to show you that practical numbers say that your estimate of how large a system your boat needs may be too large. Especially for a CD31. We have a CD30, by the way.

Divide the Ah rating by two and go for a season with it that way. Unless you plan on using a microwave while at anchor, you should be able to go smaller and cheaper! Your bimini build will be less expensive, and your cruising kitty will be happier!

Cheers, and have FUN!

Larry

[Kevin Kaldenbach]

This is one of the kits I was looking at. http://www.ebay.com/itm/285W-3x-95W-Sol ... 3f0d9ceeb8

If I can get away with 2 panels that will be great. I guess that the added usable amp hours gained from an MPPT might mean I need fewer watts.
My plans for this sailboat is to cruise it part time and leave it where ever when it time to go home.
Where can I buy a bimini with a 1 inch frame?

[chase]

Mainesail, thanks as always for some great info. I recently bought a Kyocera 135 with a regular junction box, but have yet to buy a controller. The guy that sold me my panel told me the MPPT technology was really for larger arrays and would be a waste of $$. I delayed the purchases waiting to learn more, and glad I did. I'll search for the controller you mentioned now.

I have a 210 aH bank with pretty modest needs.

KEvin, I have to agree that you might get along just fine with a single 135 W panel and potentially avoid unnecessary structural upgrades. I bought mine for $430 including shipping from affordable solar in July.

Chase

[Maine Sail]

Sorry this was a duplicate to the post below..

[tmsc]

It has been years since I have checked the prices, but Kyocera were some of the better priced ones when I bought them. That has been 10 plus years ago and I have been very very pleased with them.

[Maine Sail]

This is one of the kits I was looking at. http://www.ebay.com/itm/285W-3x-95W-Sol ... 3f0d9ceeb8

If I can get away with 2 panels that will be great. I guess that the added usable amp hours gained from an MPPT might mean I need fewer watts.
My plans for this sailboat is to cruise it part time and leave it where ever when it time to go home.
Where can I buy a bimini with a 1 inch frame?

Kevin,

While those panels may survive a for a while I would be certain they carry a warranty for the marine environment. Very few panels are covered for marine use.

Also I have seen those "Chinese" MPPT's and they are NOT worth the cardboard box they ship in and some are not even MPPT at all and behave more like a cheap shunting controller.. PLEASE be careful with solar/eBay I've seen to many of my customers get scammed on solar products.

There are plenty of legit low margin solar re-sellers who actually sell reliable, well built products.

I have seen to many of my customers scammed buying eBay solar stuff but they don't know enough about how it should operate to even challenge the eBay seller, thus the seller still has a good rating. Solar is very, very difficult to claim "performance" issues with because the sun, batteries and system are far to complex and leave way to many variables to for the average DIY to even begin to comprehend. Thus, there are a lot of snake oil solar sellers who CAN get away with selling controllers are are not MPPT, despite claims of such, or PWM's that are not PWM at all and rather shunting controllers...

$700.00+ dollars is not a gamble I would be making on no-name panels and a no-name controller. Just my $0.02.

If you stick with controllers made by Morningstar, Blue Sky, Outback or Genasun you'll be doing well. I prefer the Genasun and Morningstars over Blue Sky & Outback though as their offering for smaller systems are better, and they just work..

I use Arizona Wind Sun, Wholesale Solar and a couple of others.


P.S. I am uploading a video now of a "cheap" controller and if it uploads before I head off sailing it illustrates well why the performance of the controller is so critical...

Specifics:

375 Ah bank
80W Shell Monocrystalline Panel
FlexCharge PV-7 Shunting Controller
On voltage = 13.6V (specs say 13.5 - 13.8V)
Off Voltage = 14.4V

Bank had been at 100% SOC from shore charger. Discharged bank by 20 Ah's and left the Flex Charge to charge the bank for 4 days. At day 5 bank still not full and Ah's not yet replaced. It had been blue sky, full sun all week. Panel can put out 4.4A - 4.5A +/- in good sun or about 3-4 hours per day in Maine.

What happens with sailboats is that there is no load when left on a mooring so shunting controllers build the battery to absorption voltage then begin turning on and off to regulate the voltage. This boat has a stand by draw of 0.1A, which is a combination of the ACR relay, electronic bilge switch, stereo memory & charge controller.

The problem with On/Off controllers is that good deep cycle, gel or AGM batteries will hold a surface charge and when the charge controller turns on at higher states of charge the voltage rapidly comes up to absorption, if there is no load on the batteries. This can happen despite many Ah's still needing to flow into the bank.

Once the batteries hit absorption voltage the controller then turns off. Again, with good batteries, the time it takes for the surface charge to dissipate and fall back to the OFF voltage can take a loooong time.

This particular Flex Charge is better than many shunting controllers in that the ON voltage is approx 13.6V +/-. Some cheaper controllers, like the Sunforce units, are ON at 12.9 volts and it can take 20 minutes or more for the bank to fall that low with no loads on them. I watched an AGM bank sit at 13.0V - 13.1V for close to an hour waiting for the crappy Sunforce controller to turn back on at 12.9 volts.

In contrast the Genasun GV-10 controller never turns off and simply applies a constant voltage to the bank and the current flows as the bank will accept it. It does a true float voltage and does not rely on an ON/OFF process to prevent over charging of the batteries. This allows the bank to be re-charged significantly faster than a shunting controller. The difference in re-charge times from 80% state of charge to 100% state of charge is not measured in hours or minutes but rather DAYS!!

I have spent considerable time comparing shunting controllers and cheap PWM's to MPPT's and the real benefit, with good MPPT, is NOT in the conversion but the fact that they supply a constant voltage and do not go into an ON/OFF scenario when the banks get near full charge.

Here's a video showing the current switching ON/OFF based on the specifics above.

http://www.youtube.com/watch?v=UUaQ2FiEh2Y

If you note the time it spends ON, about 5 seconds, and OFF, about 53 seconds, it does not take a genius to figure out that with only 5 +/- good hours of charging per day how many days it will take to completely recharge the bank to 100%. And this is one of the BEST shunting controllers you can buy. This bank still had 12 Ah's to be replenished. With 5 second pulses how long will that take??

[MFC]

MS: your comments about Chinesse components is timely. I was looking at these two panels last night and wondering what difference I would see between the Kyocera and the SV panels. Both are too large (185W) but they frame the question well . . .

SV:
http://www.sunelec.com/sv-solar-panel-1 ... -1656.html

Kyocera:
http://www.sunelec.com/kyocera-solar-pa ... -1492.html

Do you see any reason to drop the extra bucks for the Kyocera? Are you just buying the name / corporate history?

Also, (this may be a contender for DQOTD but . . .) does an MPPT controler allow you to take a panel with a high Vmp (higher than 17-18 . . . say 25-35) and use it to charge a 12V system?

Thanks!

Matt

[Maine Sail]

MS: your comments about Chinesse components is timely. I was looking at these two panels last night and wondering what difference I would see between the Kyocera and the SV panels. Both are too large (185W) but they frame the question well . . .

SV:
http://www.sunelec.com/sv-solar-panel-1 ... -1656.html

Kyocera:
http://www.sunelec.com/kyocera-solar-pa ... -1492.html

Do you see any reason to drop the extra bucks for the Kyocera? Are you just buying the name / corporate history?

Also, (this may be a contender for DQOTD but . . .) does an MPPT controler allow you to take a panel with a high Vmp (higher than 17-18 . . . say 25-35) and use it to charge a 12V system?

Thanks!

Matt

Matt,

I would spend the money on a Kyocera every day over the Sunelec's, but that's me..

A good friend sells thermal imaging cameras to the solar industry to inspect the silicon crystalline cells for defects. The reputable companies all employ this technology while many of the Chinese factories selling "cheap" panels do not. While many of the top quality panels are built in China they are built to specific standards. I have seen a fair number of cheap panels not putting out anywhere near the current they are rated for. As I mentioned before also check with Sunelec to see if they will honor their warranty for a marine application. Many will not.

While you may get lucky, you may not. Kyocera, Sharp, Solar World (these are the old Seimans/Shell panels) are all top tier panels and the prices have come WAY down. A Kyocera 185W $425.00 is a steal. Those panels are also not an apples to apples comparison and the Kyocera has a higher Vmp than the Sunelec.



P.S. I finished my post above and added the video.. Nice weekend so we stayed out sailing on Monday too..